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United States Patent | 6,040,597 |
Kim ,   et al. | March 21, 2000 |
A wet etching process for establishing isolation grooves in a flash memory core wafer includes depositing nitride and/or oxide layers on a silicon substrate of the wafer, depositing a photoresist layer thereon, and then exposing predetermined portions of the photoresist layer to ultraviolet light to establish a desired groove pattern in the photoresist layer. A dry etching process is then used to remove the nitride and/or oxide layers beneath the groove pattern of the photoresist layer to thereby expose portions of the substrate. Next, the wafer is disposed in a wet etching solution such as potassium hydroxide to form grooves in the exposed portions of the silicon substrate. The wafer is oriented and disposed in the bath as appropriate for forming V-shaped grooves, such that after etching, the angled walls of the grooves can be easily exposed to a dopant beam directly above the wafer, without having to tilt the wafer or beam source. Thereby, the walls of the grooves are easily implanted with dopant.
Inventors: | Kim; Unsoon (Santa Clara, CA); Liu; Yowjuang W. (San Jose, CA); Sun; Yu (Saratoga, CA) |
Assignee: | Advanced Micro Devices, Inc. (Sunnyvale, CA) |
Appl. No.: | 023166 |
Filed: | February 13, 1998 |
Current U.S. Class: | 257/321; 257/374; 257/396; 257/397; 257/510; 257/513; 257/521; 257/527; 257/622; 257/627; 257/E21.549; 257/E21.551 |
Intern'l Class: | H01L 029/788 |
Field of Search: | 257/321,627,622,374,396,397,510,513,521,527,310 |
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